Change the MBR partition type to 0x0C when select FAT32 for installation.

Ventoy2Disk/Ventoy2Disk/PhyDrive.c

@@ -1587,7 +1587,7 @@ int InstallVentoy2FileImage(PHY_DRIVE_INFO *pPhyDrive, int PartStyle)
         memset(pData, 0, 512);
 
         pMBR = (MBR_HEAD *)pData;
-        VentoyFillMBR(pPhyDrive->SizeInBytes, pMBR, PartStyle);
+        VentoyFillMBR(pPhyDrive->SizeInBytes, pMBR, PartStyle, 0x07);
         Part1StartSector = pMBR->PartTbl[0].StartSectorId;
         Part1SectorCount = pMBR->PartTbl[0].SectorCount;
         Part2StartSector = pMBR->PartTbl[1].StartSectorId;
@@ -1751,6 +1751,7 @@ int InstallVentoy2PhyDrive(PHY_DRIVE_INFO *pPhyDrive, int PartStyle, int TryId)
     UINT64 Part2StartSector = 0;
     BOOL LargeFAT32 = FALSE;
     BOOL DefaultExFAT = FALSE;
+    UINT8 FsFlag = 0x07;
 
 	Log("#####################################################");
     Log("InstallVentoy2PhyDrive try%d %s PhyDrive%d <<%s %s %dGB>>", TryId,
@@ -1775,7 +1776,12 @@ int InstallVentoy2PhyDrive(PHY_DRIVE_INFO *pPhyDrive, int PartStyle, int TryId)
     }
     else
     {
-        VentoyFillMBR(pPhyDrive->SizeInBytes, &MBR, PartStyle);
+        if (GetVentoyFsType() == VTOY_FS_FAT32)
+        {
+            FsFlag = 0x0C;
+        }
+
+        VentoyFillMBR(pPhyDrive->SizeInBytes, &MBR, PartStyle, FsFlag);
         Part1StartSector = MBR.PartTbl[0].StartSectorId;
         Part1SectorCount = MBR.PartTbl[0].SectorCount;
         Part2StartSector = MBR.PartTbl[1].StartSectorId;

Ventoy2Disk/Ventoy2Disk/Utility.c

@@ -669,7 +669,7 @@ int VentoyFillMBRLocation(UINT64 DiskSizeInBytes, UINT32 StartSectorId, UINT32 S
     return 0;
 }
 
-int VentoyFillMBR(UINT64 DiskSizeBytes, MBR_HEAD *pMBR, int PartStyle)
+int VentoyFillMBR(UINT64 DiskSizeBytes, MBR_HEAD *pMBR, int PartStyle, UINT8 FsFlag)
 {
     GUID Guid;
 	int ReservedValue;
@@ -733,7 +733,7 @@ int VentoyFillMBR(UINT64 DiskSizeBytes, MBR_HEAD *pMBR, int PartStyle)
     VentoyFillMBRLocation(DiskSizeBytes, PartStartSector, PartSectorCount, pMBR->PartTbl);
 
     pMBR->PartTbl[0].Active = 0x80; // bootable
-    pMBR->PartTbl[0].FsFlag = 0x07; // exFAT/NTFS/HPFS
+    pMBR->PartTbl[0].FsFlag = FsFlag; // File system flag  07:exFAT/NTFS/HPFS  0C:FAT32
 
     //Part2
     PartStartSector += PartSectorCount;

Ventoy2Disk/Ventoy2Disk/Ventoy2Disk.h

@@ -238,7 +238,7 @@ const CHAR * GetBusTypeString(STORAGE_BUS_TYPE Type);
 int VentoyGetLocalBootImg(MBR_HEAD *pMBR);
 int GetHumanReadableGBSize(UINT64 SizeBytes);
 void TrimString(CHAR *String);
-int VentoyFillMBR(UINT64 DiskSizeBytes, MBR_HEAD *pMBR, int PartStyle);
+int VentoyFillMBR(UINT64 DiskSizeBytes, MBR_HEAD *pMBR, int PartStyle, UINT8 FsFlag);
 int VentoyFillGpt(UINT64 DiskSizeBytes, VTOY_GPT_INFO *pInfo);
 BOOL IsVentoyLogicalDrive(CHAR DriveLetter);
 int GetRegDwordValue(HKEY Key, LPCSTR SubKey, LPCSTR ValueName, DWORD *pValue);